A Procedural Model of Language Understanding

1. A Procedural Model ofLanguage Understanding Terry Winograd in Schank and Colby, eds., Computer Models of Thought and Language, Freeman, 1973 발표자 : 소길자

2. Index • Introduction • The presentation of meaning • Semantic analysis • The role of syntax • Limitations of the Approach

3. Introduction • Much of the research on language is based on an attempt to separate it into distinct componets • Ordering of syntactic constitunets • Define semantic relations • Model the cognitive structures

4. Introduction • 의미를 다루는 시스템들의 한계 • 배탁적으로 하나의 문장만 이해한다. • 인간의 의미해석 • 전후 문맥을 이해한다. • We make use of What has gone on to help interpret what is coming

5. Introduction • This Paper describes • an attempt to explore the interconnection between the different types of Knowledge required for language understanding • Ex) • Syntactic knowledge • “Arthur wants to see him” : “him” must refer to someone other than Arthur • Semantic knowledge • Heuristic Knowledge • Knowledge of the world • “Sam and Bill wanted to take the girs to the movies, but they didn’t have any money”

6. Introduction • It is folly to think of giving the program all the knowledge • our program • mini-world • We can give the computer a deep kind of knowledge • The world of toy robot with a simple arm

7. Introduction • Three domain • Syntactic parser • Collection of semantic routine • Cognitive deductive system • Exploring the consequences of facts • Making plans to carry out commands • Finding the answers to questions • The main emphasis • The interaction of the three domains

8. Introduction • One of the most useful organizing principles • Representation of much of the knowledge as procedures • Many other theories of language • State their rules in a form modelled on the equations of mathematics or rules of symbolic logic • To preserve the simplicity • Putting the knowledge in the form of program

9. Sample Dialogue • Q: Pick up a big red block • A: OK

10. The Representation of Meaning • A detailed world model • Describing the current state of blocks • Describing Its knowledge of procedures for changing that state and making deductions about it

11. Database of simple facts • Relationships between objects • Is , Support등 • Concepts • Block , Blue등 • Proper name of individual objects and events • B1, Table2, Event27등

12. Representations of meaning • The symbols used in these expressions represent the concepts(conceptual categories) • Concept • corresponds vaguely to a single meaning of a word • The connection is more complex • Ex) ‘truth’ ,’virtue’ , ‘democracy’

13. Representations of meaning • System’s knowledge which involves the interconnections between the concepts • In our model, these are in the form of procedures • Ex ) CLEARTOP

14. GRASP

15. This subgoal structure provides the basis for asking • “why” questions • Q : why did you put B2 on the table? • A : To get rid of it • Q : why did you get rid of it? • A : To grasp B1

16. “ A red cube which supports a pyramid”

17. Semantic Analysis • 영어 입력문장이 들어오면 이를 해석해야 내부적으로 프로그램을 생성할 수 있다. • Definition for “CUBE” ,”CONTAIN”

18. Semantic Analysis • Usage • Q: can the table pick up blocks • A:No • Table :INANIMATE • Pick up : ANIMATE • Rules are calls to program(OBJECT and RELATION) which do the appropriate checks and build semantic structure • Flexibility is done by having the definition of every word be a program

19. Semantic Analysis • Ex) • “ a big red block and a little one” • “one” must trigger a program which looks into the previous discourse • It tracks of when in the dialogue something is mentioned

20. The Role of Syntax • In process of semantic interpretation , part of the relevant input was the syntactic structure • The program contains a parser and grammar • “the three big red dogs ate a raw steak”

21. The Role of Syntax • For each unit, there is a syntactic program (written is PROGRAMMAR language) . • It will call on other such syntactic programs (and possibly on itself recursively)

22. The Role of Syntax • Our grammar takes advantage of some of ideas of Systemic Grammar(Halliday,1971) • Features • Functions • Ex) “the three big red dogs” • Features : DETERMINED, INDEFINITE,PLURAL..etc • Functions : SUBJECT

23. Vertical Line : selection • Horizontal Line : logical dependency • MAJOR : independent sentence • DECLARATIVE : she went • IMPERATIVE : go • INTERROGATIVE : did she go? • SECONDARY : “the ball which is on the table”

24. The Role of Syntax • Syntactic features are basic to description of semantic rules • Formalism for describing syntactic process • Our grammar is written in a language which was designed for the purpose, PROGRAMMAR

25. Program Organization • Parsing, semantic analysis, deduction go on concurrently throughout the understanding of a sentence • “ Put the blue pyramid on the block in the box” • Parser : “the blue pyramid ”를 Noun group으로 구분 • Semantic analysis : “the”의 대상이 되는 object를 database에서 검색

26. Program Organization • There is a continuing interplay between the different sorts of analysis, with the results of one affecting the others

27. Limitations of the Approach • The program does not attempt to handle hypothetical or counterfactual statement • Only accepts a limited range of declarative information • It cannot talk about verbal acts

28. Limitations of the Approach • Not dealing with all the implications of viewing language as a process of communication between two intelligent